Eight people, including four children, were treated after the two-car collision.
Wolverhampton Road was closed for several hours while police investigators worked at the scene.
Two cars, a Mini and Audi, were damaged by the force of the collision on Thursday.
Police said the girl was critically injured in the crash which happened at around 7.50pm.
Officers at the scene tweeted that the child had suffered a head injury.
West Midlands Police said the girl remains in hospital today.
A woman and two other children in the same car were also taken to hospital for treatment.
Four people, including two children, in the second car were also treated by paramedics.
A woman was taken to hospital as a precaution.
Police last night asked drivers to avoid the road which was shut at Pound Road towards Quinton.
Four ambulances, two paramedic officers, the Hazardous Area Response Team and a Merit Trauma Doctor attended the scene.
A West Midlands Ambulance spokeswoman said: “Upon arrival, crews found multiple patients, one of which was in a critical condition.
"Staff administered advanced trauma care to the girl, who was a passenger in one of the cars."
She was taken to Birmingham Children’s Hospital for further treatment.
The spokeswoman said a woman and two other children in the same car were treated for injuries not believed to be serious and taken to hospital.
“There were four patients in the second car involved in the collision," the spokeswoman said.
"A woman in that vehicle was assessed and taken to hospital as a precaution.
"A man and two children in the car were assessed and discharged at the scene.”